This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Connect TF - An Investigation of Function and Usability of a New Adaptable Socket System (NCT04388488), a na na study. The primary outcome is Comprehensive Lower-limb Amputee Socket Survey (CLASS) Total Score.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04388488 |
| Phase | NA |
| Condition | Prosthesis User, Amputation |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 9 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Össur Iceland ehf |
| Results posted | Yes |
2. Clinical Question
Population
The investigation concerns prosthesis users with lower-limb amputation. The registry lists “Prosthesis User” and “Amputation” as conditions and records enrollment of 9. It does not provide further participant characteristics in the information available, so eligibility details, amputation characteristics, and other features of the participants are not reported in the registry record.
Intervention
The device under investigation is the CONNECT TF adaptable socket system. The stated objective is to evaluate its function and usability, including perceived suspension, comfort, and whether fitting can be completed in a single clinical visit. Those are objectives, not findings: the registry record does not provide numerical results establishing how the system performed on these measures.
Comparator
The comparison is with a conventional handmade socket, described in the record as “Any conventional handmade socket.” The design is non-randomized, single-group, open-label, and prospective, with repeated measures described as ABBA. The record explicitly cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison.
Primary question
The primary endpoint is the Comprehensive Lower-limb Amputee Socket Survey (CLASS) total score, recorded as a percentage. The clinical question is whether participant-reported satisfaction with the socket, including perceived stability, suspension, comfort, and appearance during common activities, changes across the stated visits in the investigation of CONNECT TF and conventional sockets. No primary outcome values or analysis results are reported, so the registry record does not answer whether, or by how much, scores differed.
3. Trial Design
This completed investigation is registered as a single-group, open-label, prospective study with repeated measures described as an ABBA design. Allocation is listed as not applicable, and masking is listed as none. The record describes the investigation as comparing CONNECT TF with conventional handmade sockets, but it is not a randomized parallel-group trial. The registry specifically cautions that the arms are not a like-for-like control comparison.
The stated enrollment is 9. That figure is the enrollment recorded for the investigation; it should not be interpreted as the number contributing data to every visit or outcome. Visit-specific attendance, missing measurements, and the analysis population are not reported in the registry record. The arm-level adverse-event record separately lists 9 at risk in each named group, but that does not establish the number with complete outcome data.
The study start date is 2020-08-03, the primary completion date is 2022-01-25, and the status is completed. The record does not report a randomized assignment procedure, masking, or a parallel-group allocation. Because observations are repeated and participants may contribute measurements under both socket conditions, the data structure is intended to involve within-participant comparisons. The precise sequence implementation and the statistical handling of repeated measurements are not reported in the registry record.
The primary outcome is scheduled at Visit 1 (Baseline), Visit 2 (2 weeks), Visit 3 (6 weeks), and Visit 4 (12 weeks). The record also lists the Residual Limb Health Subscale Score (PEQ-RLH), the Prosthesis Evaluation Questionnaire (PEQ) Sounds Subscale Score, the 2-Minute Walk Test, and the Timed Up and Go Test as secondary outcomes. No outcome results or statistical analyses are reported, so the design description should not be mistaken for evidence about comparative performance.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Connect TF Group |
|---|---|
| STARTED | 9 |
| COMPLETED | 9 |
| NOT COMPLETED | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Connect TF Group |
|---|---|---|
| Participants analysed | 9 | |
| Age, Continuous | years | 62.11 (SD 9.94) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 7 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 9 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 9 |
6. Primary Endpoint
The registry lists the primary outcome as Comprehensive Lower-limb Amputee Socket Survey (CLASS) Total Score, measured over Visit 1 (Baseline), Visit 2 (2 weeks), Visit 3 (6 weeks), and Visit 4 (12 weeks).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | percentage |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the Comprehensive Lower-limb Amputee Socket Survey (CLASS) total score, summarized as a mean with standard deviation and expressed as a percentage. It is a participant-reported measure of satisfaction with a prosthetic socket for individuals with lower-limb amputation. Its questions cover perceived socket stability, suspension, comfort, and appearance during common activities. Responses are combined into a total score and converted to a percentage of the maximum possible score.
The stated scale ranges from 0% to 100%; higher percentages indicate greater satisfaction and better perceived socket performance. This makes the measure relevant to an investigation focused on socket function and usability: it captures the wearer’s assessment of aspects of the socket that may be important in everyday use. It is a subjective report, however, and should not be treated as a direct measurement of every aspect of socket function or as a substitute for the listed mobility and balance assessments.
Measurements are scheduled at Visit 1 (Baseline), Visit 2 (2 weeks), Visit 3 (6 weeks), and Visit 4 (12 weeks). Repeated measurement can describe how scores vary over the study visits, but interpreting change requires the actual scores, their variability, and a defined comparison or analysis. Those numerical results are not reported in the registry record. The record therefore identifies what the primary measure is intended to assess, but does not show the observed mean scores, differences, or their precision.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the primary outcome and the visits at which it was scheduled, but it reports no numerical CLASS results and lists zero analyses. Consequently, there is no posted estimate of socket satisfaction at any visit, no reported contrast between socket conditions, and no confidence interval or p-value with which to judge the magnitude or precision of a difference. The stated study objective cannot be treated as a result.
The distinction between design and evidence is important. A prospective repeated-measures design can collect observations over time and may permit comparisons within participants. But the record’s design is non-randomized, open-label, and explicitly not a like-for-like control comparison. Any observed change could be influenced by factors other than socket type, such as time, familiarity, expectations, or the order in which conditions were experienced. These are general interpretive concerns for an unmasked repeated-measures study, not findings reported for this investigation.
There is no basis in the registry record to say which socket produced a higher CLASS score, whether scores improved or declined, or whether any difference was important to participants. Even if a numerical difference were available, its interpretation would depend on uncertainty and the study’s analysis approach, neither of which is reported. The endpoint’s 0% to 100% scale gives the meaning of possible scores, but it does not reveal where participants’ scores fell.
The record lists additional outcomes related to residual limb health, perceived sounds, mobility, and balance. Their inclusion indicates broader areas of interest, but no results are reported for them. It is therefore not possible to compare the primary and secondary findings or to determine whether results were consistent across measures.
The adverse-event figures are a separate type of information from the effectiveness outcomes. The registry lists zero affected participants for serious events, other events, and deaths in each named group. Those entries describe what was recorded in the safety fields; they do not supply a numerical estimate of comparative socket performance. Overall, the posted record describes the question and study structure, but does not provide statistical results that would quantify an outcome difference or its precision.
9. Statistical Methods Explained
The primary endpoint is continuous: it is a percentage score, and the registry specifies the mean and standard deviation as its summary measures. These summaries answer different questions. The mean describes the central level of the recorded scores, while the standard deviation describes how much scores vary around that mean. Neither is reported numerically for this study, so neither the typical observed score nor its variability can be assessed from the registry record.
What does a mean represent?
For a continuous measure such as CLASS, the mean is an average across the observations included in an analysis. It can be a useful compact description, but it does not show the full distribution. Two sets of scores could have similar means while differing in spread or in how individual observations are distributed. The standard deviation helps describe spread, but it is not itself an estimate of uncertainty in the mean. A confidence interval is a separate statistical summary that expresses uncertainty around an estimate under the assumptions of the analysis. No confidence interval is reported for the primary outcome.
Why does repeated measurement matter?
The study is described as a prospective repeated-measures investigation. When the same participant contributes more than one measurement, those observations are related rather than independent. An analysis should account for that relationship; treating repeated observations as if they came from unrelated people can misstate uncertainty. The record does not report the statistical model or other method used to account for repeated measurements, nor does it provide an analysis of the CLASS values.
The ABBA label describes the design as recorded, but the registry information does not give enough detail to specify how sequence, period, or possible carryover effects were handled in analysis. In general, a repeated-measures comparison may be affected by changes over time, order, or participants’ experience with a device. Such effects are especially relevant when there is no masking. Whether any occurred in this investigation is not reported in the registry record.
What can a confidence interval add?
In general, a confidence interval gives a range of values compatible with the observed data and the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, but an interval does not by itself establish clinical importance or remove bias in the design. For this investigation, no effect estimate or interval is reported. The reader therefore cannot assess whether the data are compatible with a small difference, a larger difference, or little difference.
What is the role of significance testing?
A p-value, when reported, summarizes how unusual data at least as incompatible with a specified null hypothesis would be under the model assumptions. It is not the probability that the null hypothesis is true, and it does not describe the size or clinical importance of an effect. The registry lists zero analyses and reports no p-value for the primary endpoint. There is therefore no posted significance test to interpret, and the study objective should not be confused with evidence of statistical significance.
How should planning illustrations be read?
The record describes a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It defines the effect to detect as a stated fraction of the observed effect. For non-time-to-event outcomes, the illustration is expressed as participants per arm for a specified power; time-to-event illustrations use a total number of events. These are planning assumptions, not the trial’s own design justification or observed power. Numerical planning outputs and the observed effect are not reported in the registry record, so they cannot be interpreted as findings of this investigation.
More generally, planning calculations depend on assumptions about the effect size, variability, significance level, allocation, and statistical model. A calculation based on an observed effect is retrospective as a planning illustration and does not establish how likely the completed study was to detect an effect. Nor does it show that the study actually enrolled or analyzed the number suggested by a planning scenario. No sample-size justification, interim analysis plan, or detailed statistical analysis plan is reported in the registry record.
The primary endpoint is measured at several visits, while the registry also lists multiple secondary outcomes. When multiple outcomes or comparisons are tested, the chance of obtaining at least one apparently noteworthy result can increase. Statistical methods may address this through prespecified testing strategies or adjustments, but no such strategy is reported. Because no analyses are listed, there are no reported estimates, uncertainty measures, or tests from which to draw a statistical conclusion.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary CLASS outcome measured at Visit 1 (Baseline), Visit 2 (2 weeks), Visit 3 (6 weeks), and Visit 4 (12 weeks), as well as secondary measures of residual limb health, perceived sounds, mobility, and balance. This creates several possible outcome and visit comparisons. In general, testing many comparisons without an appropriate plan can increase the chance of a result that appears noteworthy by chance. The registry does not report a multiplicity strategy, such as a hierarchy of tests or an adjustment to significance thresholds; that information is not reported in the registry record.
The record also does not describe how missing outcome data were handled. It does not report visit-level completion, reasons for missing measurements, an imputation method, or sensitivity analyses. Missingness can affect estimates when the observations available for analysis differ systematically from those not available. Whether that concern applies cannot be determined from the record.
Analysis populations are not described. In particular, the record does not explain which participants or observations were included in the analysis of each endpoint, or how participants with incomplete repeated measurements were treated. Enrollment of 9 should not be read as proof that every participant contributed data at each scheduled visit. The statistical model, handling of repeated measurements, and any prespecified analysis population are not reported in the registry record.
These omissions do not establish that a particular method was or was not used outside the registry entry. They limit what can be verified from the posted record and prevent readers from assessing how missing data, repeated comparisons, and analysis inclusion may have influenced any findings.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| CONNECT TF | 0 | 9 | 0.0% |
| Conventional Socket | 0 | 9 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| CONNECT TF | 0 of 9 |
| Conventional Socket | 0 of 9 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| CONNECT TF | 0 of 9 |
| Conventional Socket | 0 of 9 |
The registry lists safety figures separately for CONNECT TF and Conventional Socket. For each group, the record lists 9 at risk for serious adverse events and 0 affected; it also lists 9 at risk for other adverse events and 0 affected. Deaths are listed as 0 in each group. These are the entries recorded for the listed groups, not a statistical comparison of safety between socket conditions.
Zero affected participants in the registry fields means no events are recorded in those fields for the groups as presented. It does not establish that the risk is absent or that the conditions have identical safety profiles. With no event counts beyond those entries and no comparative analysis, the precision of any risk estimate cannot be assessed. The record does not provide details about event definitions, collection procedures, duration of observation for safety, or participant-level exposure to each socket; those details are not reported in the registry record.
The safety figures should also be distinguished from the primary outcome. They do not indicate whether CLASS satisfaction scores differed, and they do not answer the study’s usability or mobility questions. The record lists no serious adverse-event terms. These safety entries describe reported counts, not proof that no unrecorded or unreported events occurred.
12. What the Result Does, and Does Not, Mean
The registry record establishes that an investigation of CONNECT TF and conventional handmade sockets was completed, describes its repeated-measures design, and identifies the outcomes of interest. Its primary measure, CLASS, concerns participant-reported socket satisfaction and is scheduled across four named visits. The entry also records safety counts for each named group.
It does not provide the primary outcome values, secondary outcome results, or statistical analyses. Thus, the record does not establish the direction or size of any difference, how much scores varied, or how precisely an effect was estimated. It also does not report a statistical test or confidence interval. No conclusion about comparative performance can be drawn from the stated objective or the outcome definitions alone.
The design description matters when interpreting any eventual numerical findings. This was not a randomized comparison, was open-label, and is explicitly identified in the registry as not a like-for-like control comparison. Repeated measurements can be informative, but estimates may also reflect changes over time, order, or expectations. The record does not report analyses that would allow readers to assess these possibilities.
The safety entries show zero affected participants recorded for serious adverse events, other adverse events, and deaths in each listed group. Those figures should be read as registry counts, not as proof of no risk or evidence of equivalence. The record does not include enough detail to quantify uncertainty around safety.
In general, whether a result is statistically distinguishable from no difference is separate from whether its size matters to participants. Both questions require outcome estimates and uncertainty, and clinical interpretation also depends on the meaning of the scale and the study context. Since the registry does not report numerical outcome findings, neither statistical significance nor clinical importance can be evaluated from this entry.
13. Why This Trial Matters Statistically
This investigation raises a practical measurement question: how to assess an adaptable socket system against conventional handmade sockets using both participant-reported experience and functional outcomes. CLASS focuses on satisfaction and perceived socket features, while the listed secondary measures address residual limb health, perceived sounds, mobility, and balance. Together, these outcomes represent different dimensions rather than interchangeable measures of a single concept.
The repeated-measures design is statistically relevant because observations from the same participant are related. Appropriate analysis needs to reflect that structure and distinguish changes associated with socket condition from changes associated with time or sequence. The open-label and non-randomized design also makes careful interpretation important. The registry itself warns against treating the named groups as a like-for-like control comparison.
The entry illustrates why a stated objective and a completed study status do not, on their own, provide evidence about an effect. Without outcome estimates and measures of uncertainty, readers cannot judge the direction, size, or precision of a difference. Without information about missing measurements and analysis methods, it is also difficult to assess how the data were used.
These are general statistical considerations, not criticisms based on unreported results. The record’s value is that it specifies the intended comparison, primary measure, assessment schedule, and listed safety counts. Its limitations as a results record are equally important: it does not report numerical outcome analyses, so the effectiveness question remains unanswered by the posted information.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The central limitation for interpreting this trial record is the absence of numerical outcome results. The registry names CLASS as the primary endpoint and provides its measurement schedule, but it does not report scores, contrasts, variability estimates, confidence intervals, or p-values. The secondary outcome names are listed without corresponding results. As a result, the magnitude, direction, and precision of any differences cannot be evaluated.
The design is non-randomized, open-label, and described as a single-group repeated-measures investigation. The registry cautions that the arms are not a like-for-like control comparison. This design description limits how directly a comparison can be attributed to socket type. Participants and assessors were not masked according to the record, and the influence of expectations or assessment context is not quantified.
Further design and analysis details are not reported in the registry record. These include how the ABBA sequence was implemented, how time and sequence effects were handled, which observations were included in each analysis, and how missing measurements were treated. The record does not state a multiplicity approach for the primary outcome across visits and the listed secondary outcomes, or provide a detailed statistical analysis plan.
The recorded enrollment is 9, but the record does not report visit-specific participation or outcome completeness. It is not possible to determine from the entry how many observations informed a particular endpoint or visit. The safety fields report zero affected participants for the listed event categories, but do not provide event definitions, collection details, or uncertainty estimates. These limitations concern the information available in the registry record; they do not establish what analyses or additional information may exist elsewhere.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Connect TF - An Investigation of Function and Usability of a New Adaptable Socket System — NCT04388488.
- Registry record last updated 2026-10-21; status last verified 2025-09.
- Results first posted 2026-10-21.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The record describes NCT04388488, “Connect TF - An Investigation of Function and Usability of a New Adaptable Socket System.” The sponsor is Össur Iceland ehf. The investigation is listed as completed, with enrollment of 9, a start date of 2020-08-03, and primary completion on 2022-01-25.
It is a prospective, open-label, non-randomized, single-group repeated-measures investigation described as ABBA. The devices are CONNECT TF and a conventional handmade socket. The primary endpoint is mean CLASS total score, expressed as a percentage and scheduled at Visit 1 (Baseline), Visit 2 (2 weeks), Visit 3 (6 weeks), and Visit 4 (12 weeks). Secondary outcomes cover residual limb health, perceived sounds, mobility, and balance.
The registry lists zero analyses and does not report numerical outcome results. It records zero affected participants for serious adverse events, other adverse events, and deaths in each named group. The entry therefore describes the study question, design, outcomes, and safety counts, but does not provide statistical findings for evaluating comparative performance.